Triphenylphosphine sulfide (IUPAC name: Triphenyl-λ⁵-phosphanethione) is the organophosphorus compound with the formula (C₆H₅)₃PS, usually written Ph₃PS (Ph = phenyl). It is a colourless solid, which is soluble in a variety of organic solvents.

Structurally, the molecule resemble the corresponding oxide, with ideallized C_3v point group symmetry

Symmetry group

The symmetry group of an object is the group of all isometries under which it is invariant with composition as the operation...

. It is weakly nucleophilic at sulfur.

Organic synthesis

Triphenylphosphine sulfide is useful for the conversion of epoxide

Epoxide

An epoxide is a cyclic ether with three ring atoms. This ring approximately defines an equilateral triangle, which makes it highly strained. The strained ring makes epoxides more reactive than other ethers. Simple epoxides are named from the parent compound ethylene oxide or oxirane, such as in...

s to the corresponding episulfide

Episulfide

Episulfides are a class of organic compounds that contain a saturated heterocyclic ring consisting of two carbon atoms and one sulfur atom. It is the sulfur analogue of an epoxide or aziridine. They are also known as thiiranes, olefin sulfides, thioalkylene oxides, and thiacyclopropanes.The parent...

s:

Ph₂C₂H₂O + Ph₃PS → Ph₂C₂H₂S + Ph₃PO

Analytical chemistry

In analytical chemistry

Analytical chemistry

Analytical chemistry is the study of the separation, identification, and quantification of the chemical components of natural and artificial materials. Qualitative analysis gives an indication of the identity of the chemical species in the sample and quantitative analysis determines the amount of...

, triphenylphosphine is used for the analysis of certain kinds of sulfur compounds. Elemental sulfur (S₈), as occurs in some oils, and labile organosulfur compounds

Organosulfur compounds

Organosulfur compounds are organic compounds that contain sulfur. They are often associated with foul odours, but many of the sweetest compounds known are organosulfur derivatives. Nature abounds with organosulfur compounds—sulfur is essential for life. Two of the 20 common amino acids are...

, e.g. organic trisulfides, react with triphenylphosphine to give Ph₃PS, which can be detected by gas chromatography.